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. 2014 Apr 11;4:4663. doi: 10.1038/srep04663

Figure 6. TP53 and ΔNp63 negatively regulate MDM2 and BRCA1 in basal-like cells.

Figure 6

(a) Untreated MCF10A cells express high levels of ΔNp63, and low levels of BRCA1 and MDM2. Cells plated at a low density translocate ΔNp63 to nucleoli, and elevate expression of BRCA1, and MDM2. (b) Knockdown of TP63 (siTP63) results in upregulation of BRCA1 and MDM2. (c) Western blot confirming an efficient siRNA-mediated knockdown of BRCA1 and ΔNp63 proteins, and lack of TP53 in TP53−/− MCF10A cells. Notice a higher level of ΔNp63 protein in BRCA1-depleted TP53-mutant cells. Asterisk indicates a 75 kDa band from a molecular weight marker loaded in the same lane as the siMDM2 sample. (d) TP53-deficiency in MCF10A cells leads to an increase in MDM2 mRNA level as measured by qRT-PCR. (e) Immunofluorescence staining of TP53−/− and its parental isogenic TP53+/+ MCF10A cell lines demonstrates a ubiquitous relocation of ΔNp63 protein from the nucleoplasm in TP53+/+ cells (arrowheads) to nucleoli in TP53−/− cells (arrows), and upregulation of BRCA1 in TP53−/− cells. Insets illustrate the differences at a higher magnification. Scale bars correspond to 20 µm.